package day5;

import java.util.Scanner;

/**
 * @author oldliu
 * @since 1.0
 */
public class Sum30 {
    public static void main(String[] args) {
        Scanner in=new Scanner(System.in);
        double sum=0;
        for(int i=1;i<=30;i++){
            System.out.println("请输入成绩：");
            double s=in.nextDouble();
            sum+=s;
        }
        double avg=sum/30;
        System.out.println(avg);
    }
}
